Relaxation processes at temperatures above 20 degrees C in semicrystalline polyethylene-terephthalate have been studied using thermally stimulated depolarization currents (TSDC). The discharge curve shows three relaxation peaks (alpha(c), rho(c) and rho*) whose positions and intensities depend on the polarization conditions and the crystallinity. Relaxations alpha(c) and rho(c) are heteropolar, while rho* may be homopolar or heteropolar according to the polarization temperature used. The effect of the crystallinity on these relaxations has been analysed by the thermal steps stimulation (TSS) method applied to an amorphous sample. Results show that alpha(c) is fundamentally a dipolar relaxation associated with the amorphous interlamellar zone. The relaxation rho(c) is associated with the release of a free charge trapped in the amorphous regions, and rho* is a Maxwell-Wagner-Sillars relaxation associated with crystalline amorphous interphases. For polarization temperatures above 150 degrees C, two relaxations are observed only as a consequence of overlapping rho(c) and relaxations. rho* relaxations.